Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, Japan; Center for Information and Neural Networks, National Institute of Information and Communications Technology, Suita, Japan; Research Fellow of Japan Society for the Promotion of Science, Chiyoda-ku, Japan.
J Shoulder Elbow Surg. 2022 Aug;31(8):1658-1665. doi: 10.1016/j.jse.2022.01.143. Epub 2022 Mar 1.
Deteriorated extensibility of the posterior deltoid muscle is one of the factors of posterior shoulder tightness, and improvement in its extensibility is needed. However, no study has investigated which shoulder positions effectively stretch the posterior deltoid muscle in vivo. The aim of this study was to verify the effective stretching position of the posterior deltoid muscle in vivo by shear wave elastography.
Fifteen healthy men participated in this study. The shear modulus of the posterior deltoid was measured at resting and 13 stretching positions: 60°, 90°, and 120° shoulder flexion; maximum shoulder flexion, horizontal adductions at 60°, 90°, and 120° shoulder flexion; internal rotations at 60°, 90°, and 120° shoulder flexion; and combinations of horizontal adduction with internal rotation at 60°, 90°, and 120° shoulder flexion. The shear moduli of each stretching position were compared to those of the rest. Then, among the stretching positions for which the shear modulus was significantly different from the rest, the shear moduli were compared using a three-way analysis of variance with repeated measures of the 3 factors-flexion, horizontal adduction, and internal rotation.
The shear moduli in all stretching positions were significantly higher than those of the rest, except for maximum shoulder flexion. The three-way analysis of variance with repeated measures revealed significant main effects in flexion and horizontal adduction. Comparing the flexion angles, the shear modulus was significantly higher at 90° than that at 60° and 120°. The shear modulus with horizontal adduction was significantly higher than that without horizontal adduction. Moreover, a significant two-way interaction was found only at flexion and horizontal adduction. The shear modulus with horizontal adduction was significantly higher at all angles than that without horizontal adduction at each flexion angle. Comparing the flexion angles with horizontal adduction, the shear modulus was significantly higher at 90° than that at 60° and 120°. No significant three-way interactions were found.
Shoulder flexion and horizontal adduction affected the extensibility of the posterior deltoid muscle, whereas the effect of shoulder internal rotation was limited. More precisely, maximal horizontal adduction at 90° shoulder flexion was the most effective stretching position for the posterior deltoid muscle.
肩后肌群延展性下降是导致肩部紧张的原因之一，需要改善其延展性。但是，目前尚无研究探讨活体中哪些肩部姿势可以有效地拉伸肩后肌群。本研究旨在通过剪切波弹性成像来验证活体中肩后肌群的有效拉伸姿势。
15 名健康男性参与了本研究。在休息和 13 种拉伸姿势下测量肩后肌群的剪切模量：60°、90°和 120°肩前屈；最大肩前屈；60°、90°和 120°肩前屈时的水平内收；60°、90°和 120°肩前屈时的内旋；以及 60°、90°和 120°肩前屈时水平内收与内旋的组合。将每种拉伸姿势的剪切模量与休息时的剪切模量进行比较。然后，在剪切模量与休息时的剪切模量有显著差异的拉伸姿势中，采用三因素（前屈、水平内收和内旋）重复测量的三因素方差分析来比较剪切模量。
除最大肩前屈外，所有拉伸姿势的剪切模量均明显高于休息时的剪切模量。三因素重复测量方差分析显示前屈和水平内收有显著的主效应。比较前屈角度时，90°时的剪切模量明显高于 60°和 120°。有水平内收时的剪切模量明显高于无水平内收时的剪切模量。此外，仅在前屈和水平内收之间发现有显著的双向相互作用。在所有前屈角度下，有水平内收时的剪切模量均明显高于无水平内收时的剪切模量。比较有水平内收的前屈角度时，90°时的剪切模量明显高于 60°和 120°。没有发现显著的三向相互作用。
肩前屈和水平内收影响肩后肌群的延展性，而肩内旋的影响则较为有限。更确切地说，90°肩前屈时的最大水平内收是肩后肌群最有效的拉伸姿势。
